Sometimes you can tell the difference by looking at the glass. If the edges are still square and the surface is not pitted, it should be an indication that you may have a fake piece of glass. Another way to determine if glass is real is by how it feels. Natural sea glass is pitted and has a rough feel when compared to fake sea glass that usually feels smooth. Shape can also be an aide in determining if the glass in question is natural or fake. Natural sea glass usually is not symmetrical. If you are looking at a pair of earrings made with two perfectly square pieces of glass that are the same length, thickness, and color, it is likely not natural sea glass. When trying to determine if the glass you are looking at is natural or fake, you should consider all of these factors and any other characteristics of the glass. Although glass comes in all colors, a rare color of glass sharing other characteristic of fake sea glass should be factored into your determination.
Sea glass is simply glass shards that wash up on the shores of oceans, seas, lakes and the banks of rivers. It has been in that body of water for an extended period of time, sometimes decades. Sea glass does not originate in that body of water but was put there by man. The glass no longer looks like the item is was once, and looks more like a frosty gem. This is due to exposure to different elements while submerged in the water. Related items include pottery, china and porcelain shards, toys, novelties, twisted and worn metal.
Natural sea glass is simply sea glass as defined above. So why the distinction? There are many products out there that manufacturers call sea glass that are not sea glass in the way we have defined it. Sea glass that is nature made is unaltered by man. Its appearance if formed by exposure to water currents created by nature, exposure to the sun, leeching of minerals and chemical compounds in the glass by the same in the water. These processes and exposure to different elements change the appliance of the glass over extended periods of time and it cannot be duplicated in a man-made setting.
Fake sea glass is a term we use to describe what some manufacturers refer to a sea glass, but is not sea glass as defined above. Manufacturers alter glass by different processes in an attempt to mimic sea glass. Some of these processes include tumbling glass in a rock tumbler, turning glass in a cement mixer, sand blasting the glass surface, chemically etching the glass with caustic acids, melting glass in a fire or kiln, or by a combination of these processes. The glass produced by these processes can be beautiful and can be similar to sea glass. However, this is not sea glass and should not be labeled as such. If manufacturers would call their product by what it is, i.e., man-made tumbled glass, we would have no need to call it fake.